When removal of a box changes the solution, it cannot remove the existing solution; it can only allow more possible new solutions. Conversely, adding boxes can only narrow down between existing solutions.
The special box is always placed in the bottom left for help, but another solution is "there is some box whose removal allows another solution vs. not".
Bongard Problems sorted left might be called "deceptive". Especially when the solution ruled out by the one box is the more obvious solution. |